Collapsible steering column assembly

ABSTRACT

A steering column assembly includes an upper jacket and a lower jacket partially disposed within said upper jacket. A bushing is disposed between the upper jacket and the lower jacket. The upper jacket and the lower jacket are collapsible along a longitudinal axis in response to a collision event. A first roller mechanism and a second roller mechanism are mounted to the upper jacket near a forward end and a rearward end of the bushing respectively for engaging the lower jacket in rolling engagement. The first and second roller mechanisms resist a resultant force caused by a bending moment created by a transverse load applied to a distal end of the upper jacket to minimize an increase in a sliding frictional force between the bushing and the lower jacket.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The subject invention relates generally to a steering column assemblyfor a vehicle, and more specifically to a steering column assemblycollapsible along a longitudinal axis in response to a collision event.

2. Description of the Prior Art

Automotive steering column assemblies are typically equipped withkinetic energy absorption devices. The energy absorption devices reduceinjury to a vehicle operator caused by the operator impacting a steeringwheel as a result of a collision event. Such impacts during vehiclecollision typically cause the steering column assemblies to collapse.The energy absorption devices absorb the energy transmitted through thesteering column assembly as the steering column assembly collapses.

Such energy absorbing steering columns generally include a lower jacketdisposed within an upper jacket. A bushing is disposed between the upperjacket and the lower jacket to de-lash the steering column assembly,with the bushing being coupled to the upper jacket. The upper jacket andthe bushing translate linearly through a collapse stroke during thecollision event. A load, i.e. a force, generated by the driver impactingthe steering wheel initiates the collapse stroke. The steering wheelhousing moves against a resisting or reactive force that may be producedby the energy absorption device designed to convert a portion of thedriver's kinetic energy into work. The resisting force may be generatedby systems including a plastically deformable metal element that is apart of the energy absorbing device.

During the collision event, the load is applied to the steering columnassembly, with a horizontal component of the load being appliedlongitudinally to the steering column assembly and a vertical componentof the load being applied vertically to the steering column assembly,i.e., transverse to the steering column assembly. The vertical componentof the load creates a bending moment in the upper jacket, which istransferred to the lower jacket by the bushing. Accordingly, a resultantforce is created between the upper jacket and the lower jacket to resistthe bending moment. Typically, a first resultant force is located near aforward end (nearer the front of the vehicle) of the bushing and isdirected downward, and a second resultant force is located near arearward end (nearer the rear of the vehicle) of the bushing and isdirected upward. The first resultant force and the second resultantforce increase the frictional sliding force between the bushing and thelower jacket as the upper jacket and the bushing slide relative to thelower jacket during the collision event. The increased frictionalsliding force negatively affects the performance of the energyabsorption device.

SUMMARY OF THE INVENTION AND ADVANTAGES

The subject invention provides a steering column assembly for a vehicle.The steering column assembly comprises an upper jacket. The upper jacketdefines an interior and extends along a longitudinal axis. A lowerjacket is partially disposed within the interior. The lower jacketextends along the longitudinal axis. The upper jacket is moveable alongthe longitudinal axis relative to the lower jacket. A bushing isdisposed between the upper jacket and the lower jacket. The bushingincludes a forward edge and a rearward edge spaced from the forward edgealong the longitudinal axis. A roller mechanism is coupled to the upperjacket. The roller mechanism includes a roller continuously engaging thelower jacket in rolling engagement. The roller is disposed adjacent oneof the forward edge and the rearward edge of the bushing. The rollerresists a resultant force transmitted between the upper jacket and thelower jacket in response to a load applied to the upper jackettransverse to the longitudinal axis. The roller minimizes an increase insliding friction between the bushing and the lower jacket in response tothe resultant force.

Accordingly, the roller mechanism reacts against the resultant forceoccurring between the upper jacket and the lower jacket as a result ofthe bending moment created by the transverse load applied to the upperjacket. The roller minimizes any increase in the sliding frictionalforce between the bushing and the lower jacket caused by the resultantforce so that an energy absorption device may function properly.

BRIEF DESCRIPTION OF THE DRAWINGS

Other advantages of the present invention will be readily appreciated,as the same becomes better understood by reference to the followingdetailed description when considered in connection with the accompanyingdrawings wherein:

FIG. 1 is a schematic force diagram of a steering column assembly;

FIG. 2 is side plan view of the steering column assembly;

FIG. 3 is an enlarged fragmentary side plan view of the steering columnassembly;

FIG. 4 is an enlarged fragmentary bottom plan view of the steeringcolumn assembly shown in FIG. 3; and

FIG. 5 is a fragmentary side plan view of an alternative embodiment ofthe steering column assembly.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the Figures, wherein like numerals indicate correspondingparts throughout the several views, a steering column assembly is showngenerally at 20. The steering column assembly 20 is for a vehicle androtatably supports a steering wheel (not shown) as is well known.Referring to FIG. 1, the steering column assembly 20 is collapsiblealong a longitudinal axis L in response to a driver impacting thesteering wheel during a collision event. The impact of the driveragainst the steering wheel transmits a load, i.e., a force, to thesteering column to initiate the collapse stroke. The load applied to thesteering column assembly 20 includes a longitudinal component 22 FLalong the longitudinal axis L and a vertical component 24 transverse tothe longitudinal axis L. The steering column assembly 20 includes anenergy absorption device (not shown) for resisting the collapse strokeas is well known.

Referring to FIG. 2, the steering column assembly 20 comprises an upperjacket 26. The upper jacket 26 defines an interior 28, and extends alongthe longitudinal axis L. A lower jacket 30 is partially disposed withinthe interior 28 of the upper jacket 26. The lower jacket 30 also extendsalong the longitudinal axis L. The upper jacket 26 is moveable along thelongitudinal axis L relative to the lower jacket 30 during the collapsestroke. While the steering column assembly 20 of the subject inventionis described and shown as including the upper jacket 26 defining theinterior 28 with the lower jacket 30 partially disposed therein, itshould be appreciated that the configuration of the upper jacket 26 andthe lower jacket 30 may be reversed and still fall within the scope ofthe subject invention. In other words, the lower jacket 30 may definethe interior 28 and the upper jacket 26 may be partially disposed withinthe interior 28.

A bushing 32 is disposed between the upper jacket 26 and the lowerjacket 30. Preferably, the bushing 32 is injection molded into placebetween the upper jacket 26 and the lower jacket 30. However, it shouldbe appreciated that the bushing 32 may be manufactured and installed insome other manner. Preferably, the bushing 32 is coupled to and moveablewith the upper jacket 26 along the longitudinal axis L. However, itshould be appreciated that the bushing 32 may be coupled to the lowerjacket 30, with the upper jacket 26 moveable relative to both thebushing 32 and the lower jacket 30 during the collapse stroke. Thebushing 32 includes a forward edge 34 and a rearward edge 36. Theforward edge 34 is disposed nearer the front of the vehicle, while therearward edge 36 is disposed nearer the rear of the vehicle. Therearward edge 36 is spaced from the forward edge 34 a bushing length 38along the longitudinal axis L. The bushing length 38 extends between theforward edge 34 and the rearward edge 36 of the bushing 32 along thelongitudinal axis L.

The lower jacket 30 includes a forward end 40. The forward end 40 of thelower jacket 30 is disposed nearer the front of the vehicle. At leastone mounting bracket is coupled to the lower jacket 30 at a firstattachment point 42 adjacent the forward end 40 of the lower jacket 30.

The mounting bracket is configured for attachment to the vehicle and maybe configured and attached to the vehicle in any suitable manner. Theupper jacket 26 is coupled to the at least one mounting bracket at asecond attachment point 44. The second attachment point 44 is axiallyspaced from the first attachment point 42 a pre-determined firstdistance 46. Preferably, the at least one mounting bracket includes afirst mounting bracket 48 and a second mounting bracket 50, with thefirst mounting bracket 48 coupled to the lower jacket 30 adjacent to theforward end 40 of the lower jacket 30 at the first attachment point 42and the second mounting bracket 50 coupled to the upper jacket 26 at thesecond attachment point 44.

A release module 52 releasably attaches the second mounting bracket 50to the vehicle prior to a collision event. The release module 52releases the second mounting bracket 50 from the vehicle in response tothe collision event. Accordingly, the release module 52 interconnectsthe vehicle and the second mounting bracket 50 at the second attachmentpoint 44.

The upper jacket 26 includes a distal end 54. The distal end 54 of theupper jacket 26 is disposed nearer the rear of the vehicle, with thesteering wheel attached to the distal end 54 as is well known. Thedistal end 54 of the upper jacket 26 is axially spaced from the secondattachment point 44 along the longitudinal axis L a pre-determinedsecond distance 56. The rearward edge 36 of the bushing 32 is spacedfrom the first attachment point 42 a pre-determined third distance 58.

Referring back to FIG. 1, the vertical component 24 of the load appliedto the steering column assembly 20 by the driver during the collisionevent produces a bending moment in the upper jacket 26. The bendingmoment creates a first resultant force 60 near the forward edge 34 ofthe busing on a top side of the steering column assembly 20, and asecond resultant force 62 near the rearward edge 36 of the bushing 32 ona bottom side of the steering column assembly 20. In order to resist thefirst resultant force 60 and the second resultant force 62, the steeringcolumn assembly 20 of the subject invention disposes a roller mechanism66, 68 near at least one of the first resultant force 60 an the secondresultant force 62.

Referring back to FIG. 2, the roller mechanism 66, 68 is coupled to theupper jacket 26. The roller mechanism 66, 68 includes a roller 64, withthe roller 64 continuously engaging the lower jacket 30 in rollingengagement. The roller 64 engages the lower jacket 30 adjacent one ofthe forward edge 34 and the rearward edge 36 of the bushing 32. Theroller 64 resists one of the resultant forces 60, 62 transmitted betweenthe upper jacket 26 and the lower jacket 30 in response to the verticalcomponent 24 of the load applied to the upper jacket 26 transverse tothe longitudinal axis L. By resisting the resultant forces 60, 62, theroller 64 minimizes an increase in sliding friction between the bushing32 and the lower jacket 30 in response to the resultant force, therebyimproving performance of the energy absorption device by eliminating orminimizing the frictional sliding loads generated by the first resultantforce 60 and the second resultant force 62.

Preferably, the roller mechanism 66, 68 includes a first rollermechanism 66 and a second roller mechanism 68. The first rollermechanism 66 is disposed adjacent to the forward edge 34 of the bushing32 near the first resultant force 60. The second roller mechanism 68 isdisposed adjacent to the rearward edge 36 of the bushing 32 near thesecond resultant force 62. The first roller mechanism 66 and the secondroller mechanism 68 are vertically disposed on opposite sides 70, 72 ofthe tipper column jacket. Accordingly, it should be appreciated that theupper column jacket includes an upper side 70 and a lower side 72. Thelower side 72 of the upper jacket 26 is disposed vertically below theupper side 70. The first roller mechanism 66 is disposed on the upperside 70 of the upper jacket 26, and the second roller mechanism 68 isdisposed on the lower side 72 of the upper jacket 26.

The roller mechanism 66, 68 includes a roller bracket 74 mounted to theupper jacket 26. The roller bracket 74 may be configured in any suitablemanner, but must be rigidly attached to the upper jacket 26 to be ableto transmit vertical loads to the upper jacket 26. The roller bracket 74includes a ramp 76 defining an inclined angle 78 relative to the lowerjacket 30. The inclined angle 78 is between the range of four degrees(4°) and five degrees (5°) relative to the lower jacket 30.

The roller mechanism 66, 68 includes an axle 80 coupled to the rollerbracket 74. The axle 80 is in engagement with the ramp 76. Accordingly,the roller 64 includes a central bore 82. The axle 80 extends throughthe central bore 82, with the axle 80 rotatably supporting the roller64. The axle 80 includes a planar surface 84 abutting the ramp 76.Preferably, the axle 80 includes a square cross section; however, itshould be appreciated that the cross section of the axle 80 may be otherthan square so long as the cross section presents a planar surface 84 toabut the ramp 76.

The planar surface 84 reacts against the ramp 76 disposed at theinclined angle 78 relative to the lower jacket 30 and prevents the axle80 from rotating. The force of gravity causes the roller 64 to seatagainst the lower jacket 30 and the planar surface 84 of the axle 80 towedge against the ramp 76, thereby de-lashing the roller mechanism 66,68 and removing all clearance between the lower jacket 30 and the rollermechanism 66, 68.

Upon the driver impacting the steering wheel during the collision event,the first resultant force 60 and the second resultant force 62 reactagainst the first roller mechanism 66 and the second roller mechanism 68respectively. The rollers 64 of the first roller mechanism 66 and thesecond roller mechanism 68 roll on an outside surface of the lowerjacket 30 and minimize or eliminate the frictional sliding load thatwould otherwise be generated by the bending moment created by thevertical component 24 of the impact load. The inclined angle 78 of theramp 76 is slight enough to prevent the axle 80 form climbing the ramp76 in response to the first resultant force 60 and the second resultantforce 62.

Referring to FIGS. 3 and 4, the roller mechanism 66, 68 may include aspring 86. The spring 86 interconnects the axle 80 and the rollerbracket 14. The spring 86 urges the axle 80 into engagement with theramp 76 and urges the roller 64 into engagement with the lower jacket30. As shown, the spring 86 includes a formed bar spring 86interconnecting the axle 80 and the roller bracket 74. However, itshould be appreciated that the spring 86 may include some other style ofspring 86 and may be configured other than shown and described herein.

Referring to FIG. 5, an alternative embodiment of the steering columnassembly is shown generally at 120. Features of the alternativeembodiment of the steering column assembly 120 similar to features ofthe steering column assembly 20 are referenced utilizing the identicalreference numeral utilized for the steering column assembly 20 precededby the numeral 1. For example, the steering column assembly 20 includesthe roller 64, accordingly the alternative embodiment of the steeringcolumn assembly 120 utilizes the reference numeral 164 to identify theroller 164 in the alternative embodiment of the steering column assembly120.

In the alternative embodiment of the steering column assembly 120, theaxle 180 includes a circular cross section and is rotatably supported bythe roller bracket 174, i.e., the axle 180 is rotatably fixed to theroller bracket 174. The axle 180 supports the roller 164 in spacedrelationship relative to the lower jacket 130. Accordingly, the roller164 and the lower jacket 130 define a separation distance 188therebetween during normal operating conditions. However, the spacedrelationship is very minimal. Accordingly, the roller 164 will bebrought into contact with the lower jacket 130 in response to minimalflexure of the steering column assembly 120 as the vertical component124 of the load creates a bending moment in the steering column assembly120. It should be noted that the alternative embodiment of the steeringcolumn assembly 120 does not include the angled ramp 176 to ensure thatthe roller 164 engages the lower jacket 130 at all times.

The invention has been described in an illustrative manner, and it is tobe understood that the terminology which has been used is intended to bein the nature of words of description rather than of limitation. As isnow apparent to those skilled in the art, many modifications andvariations of the present invention are possible in light of the aboveteachings. It is, therefore, to be understood that within the scope ofthe appended claims, wherein reference numerals are merely forconvenience and are not to be in any way limiting, the invention may bepracticed otherwise than as specifically described.

1. A steering column assembly for a vehicle, said assembly comprising:an upper jacket defining an interior and extending along a longitudinalaxis; a lower jacket partially disposed within said interior andextending along said longitudinal axis with said upper jacket moveablealong said longitudinal axis relative to said lower jacket; a bushingdisposed between said upper jacket and said lower jacket with saidbushing including a forward edge and a rearward edge spaced from saidforward edge along said longitudinal axis; a roller mechanism coupled tosaid upper jacket and including a roller continuously engaging saidlower jacket in rolling engagement adjacent one of said forward edge andsaid rearward edge of said bushing for resisting a resultant forcetransmitted between said upper jacket and said lower jacket in responseto a load applied to said upper jacket transverse to said longitudinalaxis to minimize an increase in sliding friction between said bushingand said lower jacket in response to said resultant force.
 2. Anassembly as set forth in claim 1 wherein said roller mechanism includesa first roller mechanism disposed adjacent said forward edge of saidbushing and a second roller mechanism disposed adjacent said rearwardedge of said bushing.
 3. An assembly as set forth in claim 2 whereinsaid first roller mechanism and said second roller mechanism arevertically disposed on opposite sides of said upper jacket.
 4. Anassembly as set forth in claim 3 wherein said upper jacket includes anupper side and a lower side disposed vertically below said upper sidewith said first roller mechanism being disposed on said upper side andsaid second roller mechanism being disposed on said lower side.
 5. Anassembly as set forth in claim 1 wherein said roller mechanism includesa roller bracket mounted to said upper jacket.
 6. An assembly as setforth in claim 5 wherein said roller bracket includes a ramp defining aninclined angle relative to said lower jacket.
 7. An assembly as setforth in claim 6 wherein said inclined angle is between the range offour degrees (4°) and five degrees (5°).
 8. An assembly as set forth inclaim 6 wherein said roller mechanism includes an axle coupled to saidroller bracket and engaging said ramp.
 9. An assembly as set forth inclaim 8 wherein said roller includes a central bore with said axleextending through said central bore to rotatably support said roller.10. An assembly as set forth in claim 8 wherein said axle includes aplanar surface abutting said ramp.
 11. An assembly as set forth in claim8 wherein said roller mechanism includes a spring interconnecting saidaxle and said roller bracket to urge said axle into engagement with saidramp and urge said roller into engagement with said lower jacket.
 12. Anassembly as set forth in claim 1 wherein said lower jacket includes aforward end and wherein said assembly further comprises at least onemounting bracket coupled to said lower jacket at a first attachmentpoint adjacent said forward end and configured for attachment to thevehicle.
 13. An assembly as set forth in claim 12 wherein said upperjacket is coupled to said at least one mounting bracket at a secondattachment point axially spaced from said first attachment point apre-determined first distance.
 14. An assembly as set forth in claim 13wherein said upper jacket includes a distal end axially spaced from saidsecond attachment point along said longitudinal axis a pre-determinedsecond distance.
 15. An assembly as set forth in claim 14 wherein saidbushing includes a length extending between said forward edge and saidrearward edge along said longitudinal axis.
 16. An assembly as set forthin claim 15 wherein said rearward edge of said bushing is spaced fromsaid first attachment point a pre-determined third distance.
 17. Anassembly as set forth in claim 16 wherein said bushing is coupled to andmoveable with said upper jacket along said longitudinal axis.
 18. Anassembly as set forth in claim 13 wherein said at least one mountingbracket includes a first mounting bracket coupled to said lower jacketadjacent said forward end of said lower jacket at said first attachmentpoint and a second mounting bracket coupled to said upper jacket at saidsecond attachment point.
 19. An assembly as set forth in claim 5 whereinsaid roller mechanism includes an axle rotatably supported by saidroller bracket.
 20. An assembly as set forth in claim 19 wherein saidroller includes a central bore with said axle extending through saidcentral bore to rotatably support said roller.
 21. An assembly as setforth in claim 20 wherein said roller is spaced from said lower jacket apredetermined separation distance.